Recently, in automobile parts, parts for electronics, precision machinery components and the like, which are increasingly required to reduce the weight, a high-strength lightweight Al alloy material is being widely used.
The mechanical properties at ordinary temperature of the Al alloy are remarkably improving in recent years but are still insufficient compared with a high-strength steel, and use of this alloy is limited. For example, even a so-called A7000-series Al alloy widely used as a high-strength Al alloy is not satisfied with its strength and is limited in the range of use.
As for conventional alloys by melting and casting, there is a limit to the significant improvement of mechanical properties such as strength. Therefore, a process of obtaining an A7000-series Al alloy as a rapidly solidified powder by an atomization process has been heretofore proposed with an attempt to more increase the strength. According to the rapid solidification process, a content of the alloy element can be more increased than that in the Al alloy by conventional melting and casting. Consequently, an Al alloy with excellent strength can be obtained by rapidly solidifying an Al alloy containing a large amount of such an alloy element into a powder and subjecting this to solidification and forming.
For example, in Patent Document 1, a component composition of an A7000-series Al alloy is prepared by blending a specific amount of Ag, and a rapidly solidified alloy powder of this component composition obtained by an air atomization process is formed into a solidified shaped body by powder metallurgy process by extrusion. Incidentally, it is indicated that when this shaped body is subjected to a homogenization treatment and an aging hardening treatment, the tensile strength of the shaped body material after T6 heat treatment can be increased up to about 900 MPa. In Patent Document 1, as regards a more specific composition of the A7000-series Al alloy, a rapidly solidified powder of the A7000-series Al alloy containing from 5 to 11% of Zn, from 2 to 4.5% of Mg, from 0.5 to 2% of Cu and from 0.01 to 0.5% of Ag, with a remainder consisting substantially of Al is disclosed.    Patent Document 1: JP-A-7-316601